The Earth

The Earth is part of the solar system which is composed of the sun, other planets, and moons among other astronomical features. However, unlike other planets the Earth possesses a great deal of uniqueness due to the presence of life, something that has not been found somewhere else on any other part of the solar system. The formation of then solar system resulted from a series of events that culminated with the onset of life which was a spontaneous occurrence resulting from the events in the solar system.

The changes on the Earth shaped life and the onset of life also began to shape the Earth, the two processes continue concurrently to date; in other words geology and biology continue to influence each other causing the continued gradual change on life known as evolution. Initially the Solar system existed as a large rotating cloud of dust, rocks and gases (hydrogen and helium) which resulted from the Big bang. This cloud; the Solar nebular is what developed into the solar system. A nearby star was destroyed in an explosion sending shock waves into the solar nebular.

The solar nebular started rotating and gaining momentum with most mass concentrating on the middle due to gravity, rotation and inertia. The middle began to heat up due to the rotation and since the energy was not being released to the outer space it led to the nuclear fusion of hydrogen and helium atoms, it later contracted resulting in the formation of the Sun which is the center of the solar system. The gravity from the sun caused objects from the perturbed solar system to condense into protoplanets which formed rings and rotated around the sun.

The Earth was one of this protoplanets. About 150 kilometers from both the Earth and the Sun there was a planet smaller than the Earth called Theia which got destabilized from its orbit as the Earth increased in mass and size. It began to swing back and forth and finally collided with the Earth but at low speed and also at a low oblique angle such that the earth was not destroyed. However, the crust of the planet was thrown into space and later condensed to form the Moon. The rest of it sank into the Earth crust.

The collision also caused the Earth to tilt on its axis; this resulted into seasons. The Earth was mainly molten at this stage due to heat generated by the pressure and the radioactive reactions. The heavy elements like Iron began to sink towards the middle of the molten Earth due to its rotation. The Earth formed layers in its structure at this stage. It also developed its own gravitational pull and hence managed to hold hydrogen and helium around its surface, this became the Earth’s first atmosphere. Temperatures dropped drastically and the Earth crust solidified.

More water was introduced from the outer space by Bolide collisions involving asteroids. The Earth cooled, clouds formed, rain began to fall and oceans were formed. At this time the earth got its second atmosphere which was composed of Ammonia, Methane, Water vapor, Carbon (iv)oxide and Nitrogen. Due to absence of oxygen in the atmosphere there was no ozone layer and the ultra-violet rays flooded the earth’s surface. A molecule with the ability to replicate itself was formed, this molecule resembled the present day DNA.

This was the initial stages of the development of life. More complex molecules were also formed at this stage from already existing molecules in the atmosphere and this were the building blocks of the life, this included proteins and other building blocks of life. A protein and phospo-lipid layer was formed around the replicator in water resulting in the protocells. The protocells were the first living organisms and they only existed in water. Evolution began whereby the simple molecules and protocells formed more complex and advanced versions of them.

Prokaryotes, which lack the nucleus and membrane, bound organelles like the chloroplasts and the mitochondria later evolved into the eukaryotes. This occurred by either the prokaryote trying to engulf another or an attempt by the other to parasitize it, when the attempt failed they ended up coexisting together symbiotically. The host cell then took the DNA of the engulfed cell and both ended up as a single cell with organelles. Autotrophic cyanobacteria emerged at this time and began to carry out photosynthesis.

This resulted in the production of oxygen gas and the Earth’s third atmosphere. Oxygen gas formed the ozone layer which reduced the amount of u. v radiation reaching the Earth surface hence allowed the colonization of the water bodies by the living organisms. This was the first major impact that the living organisms were making in shaping the earth. Besides the positive impact of the oxygen gas it increased to dangerous levels leading to the death of much of the living organisms at the time. The ones which could withstand the toxic levels of oxygen survived.

The single celled organisms later began to co-exist as a colony. With time the colonies became more advanced and began division of labor where cells where assigned different roles. This was the development of multicellularity in the living organisms. The process of evolution continued and living organisms diversified forming more advanced forms of themselves, however the process was punctuated by extinction of some species which could not cope with some conditions in their environment.

Living organisms moved to land with time and colonized it as they developed the necessary adaptations to cope. The events on Earth brought about the onset of life, the life also began to induce changes on Earth’s both. Both geological and biological events shape the Earth to date.

Work cited

Peter J. Cattermole . Christopher A. McRoberts. 2001: Building Planet Earth: Five Billion Years of Earth History. New York. Lv Berkner, Lc Marshall 1964. The history of oxygenic concentration in the earth’s atmosphere Dallas Texas www. lsa. umich.edu/UofM/Content/geo/document/GeoSci_Courses_for_Non-Majors. pdf Richard Huggett. 1988. Events in Earth History . New York Alfven, Hannes; Gustaf Arrhenius 1976. Origin of the earth’s ocean and atmosphere, Evolution of the Solar System. Washington, D. C. Wilde, Simon A. ; John W. Valley, William H. Peck, and Colin M. Graham. 2001. Evidence from detrital zircons for the existence of continental crust and oceans on the Earth. Washington, D. C. Fortey, Richard. 1997. “Dust to Life”, A Natural History of the First Four Billion Years of Life on Earth. New York